Art of cracking hydrocarbons



1. W. COAST, JR.

ART 0F CRACKING HYDROCABBONS.

APPLlcATloN FILED APR.9, 1911. RENEwED1uNE14, 1920.

Patented Aug. 3, 1920.

2 SHEETS-SHEET l.

VX Z

Patented ug. 3, 1920.

2 SHEETS-SHEET 2- UNITED STATES PATENT, oFFlcE.

JOHN' W. COAST, JR., OF TULSA, OKLAHOMA, ASSIGNOR. T0 THE PROCESS COMPANY, A

\ CORPORATION OF MARYLAND. i

ART 0F CRACKING I-IYDROCARBONS.

Specification of Letters Patent.

Patented Aug. 3, 1920.

Application iled April 9, 1917, Serial No. 160,822. Renewed .Tune 14, 1920. Serial No. 389,009.

To all 'whom t may concern Be it known that I, JOHN W. COAST, J r., a citizen of the United States of America, a resident of Tulsa, in the county of Tulsa, State of Oklahoma, have invented certain new and useful Improvements in the Art of Cracking Hydrocarbons, of which the following is a full, clear, and exact description, reference being hadto the accompanying drawings, forming a part of this specification. My invention relates to improvements in the art of cracln'ng highboiling point petroleum hydrocarbons. In cracking hydrocarbons of this kind to obtain cracked gasolene it has been found necessary to condense the unconverted, or partially converted, high boiling point fractions before they reach the condenser from which the low boiling point product is recovered. In actual practice, the vapor is usually conducted away from the still and then through one or v more reflux condensers whereby the high boiling point fractions are condensed, the condensate being conducted from the reflux condensersto the still for further treatment.

The main object of this invention is to condense the high boiling point fractions in the upper portion of .the still, permitting the condensate to drop back into the liquid, and conducting the remaining vapor from the still to the condenser, from which the product is recovered. To accomplish this, the upper portion of the still is maintained in a relatively cool condition, the vapor being deflected andconducted along the cool portion of the still in such a manner that the temperature of all of the vapor is very Inaterially reduced, thereby condensing thehigh boiling point fractions before the vapor passes from the still. Owing to the peculiar manner in which the vapor is baffled, de-

flected, and brought into contact with the cool parts of the still, the temperature of the vapor may be reduced to such a low degree that only the desired low boiling point fractions will escape from the still. In this event, it will be unnecessary to pass the vapor through the ordinary reflux condensers.

In the preferred form of the invention, a relatively cool Huid, preferably a high boiling point hydrocarbon liquid, is introduced into the vapor confined in the still. This liquid serves as a condensing medium for the taken through the middle portion of the still, showing the bailes and the restricted vapor ypassage'ways at the upper portion of the still.

Fig. lIII is an enlarged longitudinal section of the still.

To illustrate the invention, I have shown a cracking still l, in the form of a large boiler, arranged above a heating chamber 2,

and connected by means of a vapor pipe 3 to a water cooled condenser 4 from which the low boiling point product is recovered.

. The apparatus shown is particularly adapted for use in cracking high boiling point products of distillation, such, for example, as the distillates or residues resulting from the distillation of crude petroleum. The contents of the still are, of course, maintained under pressure, and any desired pressure may be obtained by regulating a valve 5in the vapor pipe 3. The pressure in the still is preferably greater than 50 'pounds per square inch, for example, about 80 pounds per square inch, and the temperature of the liquid contents of the still preferably ranges from about 600O F. to about 8000 F. The low boiling point vapor, passing from the liquid, .flows through the relatively cool upper portion of the still and is discharged into the vapor pipe 3. The relatively high boiling point fractions are condensed in the still, as will be hereinafter described, and permitted to drop back into the liquid. This high boiling point condensate includes some heavy coke-forming fractions commingled with lighter fractions rwhich `TheI vapor cooling means includes a large vapor trap, in the form 'of an inverted trough, located inthe upper `portion of the still. This vapor trap comprises a longitudinal baille member 7 which extends approximately from one end of the still to the other, said baille member being'semi-circular in cross section so as to conform approximately to the shape of the top wall of the still. The baille member 7 is separated from the top wall of the still to form a restricted vapor passageway 8. End baille members 9, located at the ends of the lo-ng baille member 7, are separated from the end walls of the still to form restricted passageways 10 for the rising vapor flowing to the restricted passageway 8.- The lower edges of the end baille members 9 are located above and adjacent to the surface of the liquid in the still to form restrictedl outlet ports 11 for the vapor flowing tothe end passagewa s 10. i

n air cooled tower 12 extends upwardly from the top wall of the still to receive the vapor ilowing from the long restricted passageway 8. 13 designates a baille device arranged in the air cooled tower and separated from the upright wall thereof to provide a restricted annular passageway 14 for the rising vapor. n The baille device 13 is in the form of a receptacle, open at the top to receive the vapor and closed at the bottom to exclude the rising vapor.

To prevent the vapor from lescaping around the lower longitudinal edges of the long baille member 7, vthese edges are preferably located below the level of the liquid in the still, as shown most clearly in Fig. II.' Condensate troughs 15, located adjacent to the longitudinal edges of the baille member 7, are inclined toward the ends of the still. The condensate, flowing from the baille member 7, drops into the troughs 15,

'and the heavy coke-forming fractions con'- tained in the condensate are thereby conducted to the end portions of the still, where they will settle upon the still bottom 'at points above the lwalls 6. These heavy fractions dro-p by gravity, and they accumulate on the protected portions of the still bottom, instead of being permitted to collect at ptopts where the heat is transmitted to the s i Instead of being protected, the upper portion of the'still is subjected to the coolin action of relatively cool air currents. jacket 16, approximately'semi-circular in cross section, is preferably arranged over the correspondingly shaped upper portion of the still to provide an air passageway 17 and air under pressure may be discharged from, a pipe -18 to the passageway 17 for \the purpose of creating a forced draft of cool air over the top wall of the still. A perforated discharge pipe 19, located in the restricted passageway 8, is connected to a supply pipe 20 through which a relatively cool fluid is conducted for the purpose of cooling the Vapor. This relatively cool fluid is, preferably, a high boiling point hydrocarbon liquid, and 1t is discharged through the numerous perforations in the pipe 1,9

so as to cool the vapor, at the same time cooling the upper portion of the still. This hydrocarbon liquid, in addition to serving as a cooling medium, is subjected to the cracking process carried on in the still, and it eventually forms part of the low boilingpoint product.

A perforated discharge member 22 (Fig. III), arranged in the cylindrical baille device 13, is connected toa steam piplp 23 pro-vided with a regulating valve 24. elatively cool steam, passing from the discharge member 22, is forced into the vapor in the cylindrical balHe device 13.

The vapor rising from the liquid under the long baille member 7 is trapped by the bailles 9. This vapor passes under the lower. edges of the end bailles 9, upwardly through the restricted end lpassageways 10, through the long restricted passageway 8 above the baille 7, thence upwardly in the restricted passageway 14, downwardly in the cylindrical baille device 13 and then into the vapor pipe 3. The upper portion of the still is maintained in a-relatively cool condition, as previously pointed out, and the vapor. is baffled, deflected, brought into contact with the cool parts of the still, and otherwise acted upon in such a manner that the temperature of all of the vapor is greatly reduced. As a consequence, the high boiling point hydrocarbons are condensed, in the still, and all of the vapor escaping from the still may be condensed in thel water cooled condenser 4 from which the cracked product is recovered.

The condensate formed in the cylindrical baille device 13 passes through a liquid seal or trap 25 and drops onto the long baille member 7. The high boiling point condensate formedv in the restricted passageway 8, between the top wall of the still and the baille 7 flows downwardly on the top face of the baille 7 and commingles with the liquid in the still. The, heavy coke-forming fractions are conducted, by the inclined troughs 15, tothe end portions of the still, where they drop by gravity to the protected end portions of the still bottom.,

In treating petroleum hydrocarbons to i them into lighter fractions. By reducing the temperature of the vapor in the still as herein shown and described, all of the vaporized fractions having a normal end or dryf point higher than 5000 b. may be condensed in the still. All of the vapor passing from the still will then be free from the undesirable heavy fractions, and the desired product may be obtainedby condensing all of this vapor in the water cooled condenser 4. A

rl`he condensing action at the upper portion of the still can be varied by regulating the How of relatively cool steam, air or liquid, each of which serves as a cooling medium for the vapor. lt will, therefore, be apparent that the apparatus can be easily adjusted or regulated to condense, or knock haelt all of the fractions having a boiling point higher than about 500O claim:

l. ln the art of cracking petroleum hydrocarbons, the method which comprises vaporizing a hydrocarbon liquid in a horizontal cylindrical still, maintaining the liquid and vapor under pressure, maintaining the upper portion 'of the still in a relatively cool condition, deecting vapor to an end portion of the still and then along the relatively cool upper portion so as to condense the vaporized fractions having relatively high boiling points, and conducting the remaining vapor from the still to a condenser.

2. ln the art of cracking petroleum hy drocarbons, the method which comprises vaporizing a hydrocarbon liquid in a hori- Zontal cylindrical still, maintaining the liquid and vapor under pressure, maintaining the upper portion of the still in a relatively cool condition, deflecting vapor to an end portion of the still and then along said relatively cool upper portion, into an air cooled tower at the top of the still, thence upwardly along the upright wall of said tower and downwardly near the center of the tower, thereby condensing the vaporized fractions having relatively high boiling points, and conducting the remaining vapor from said air cooled tower to the condenser,

3. ln the art of cracking petroleum hydrocarbons, the method which comprises vaporizing a hydrocarbon liquid in a still, maintaining the liquid and vapor under pressure, forcing relatively cool air along the outer face of the upper portion of the still, introducing a relatively cool fluid into the still at the upper portion thereof, trapping the vapor and deflecting. it to the relatively cool upper portion of the still, then conducting the vapor along said relatively cool portion so as to condense the fractions having relatively high boiling points and conducting the remaining vapor from the still to the condenser.

ln testimony that l claim the foregoing l. hereunto afliX my signature.

Joint w. coas'r, n. 

